Actually, I have stuff like this littered throughout my code. When I'm developing, I need something to happen to tell me the if statement didn't execute. If the statement is something like this:

if ($foo) {
   print LOG "Exit condition $foo reached.\n";
   exit 0;
}
[download]

...then no big deal. If the code is more like this:

if ($line =~ /\w+sql=\w+/i) {
   $db = "mysql";
   $db_loc = (split(/=/, $line))[1];
}
[download]

...then during the testing period I need to account for a failure condition.

else {
   print DEBUG "Error: Couldn't parse a database out of line ($line)\n
+";
}
[download]

In the field, I'd probably delete the error message, but there's a good chance that I'd leave the else statement in so I could re-enable it later if neccessary.